Hey Shango. I think the fact they use 262.5KHz IF frequency might have to do with the harmonics generated by a mechanical ignition in old-style cars. Opening and closing contacts in the HV distributor generate very dirty square wave signals which are rich in harmonics, or so I've learned. Using the 262.5KHz might be an attempt to avoid those harmonics creating that annoying buzzing noise one heard in old CRT tv's and tube radios when a car drove by. Like your videos as always :) they're real treasures of fun and info mixed in the right proportions
Weren't all General Motors radios made by Delco? This one appears to have been an aftermarket radio probably installed by the dealer as radios were not standard?
I get the heebie-jeebies every time you poke your index finger into a radio or TV. Amazing that you're still able to do so. At least with a transistor car radio you're not going to get zapped. Take care! Also when I was servicing RCA 16mm projectors, they used those bakelite body and red end goop capacitors, they typically lost 90% of their capacitance in the first year. Another tip: car radios typically had "belt and suspenders" biasing, robust enough so you could swap in silicon transistors into the low power stages with no problem. For instance on a typical TransOceanic 1000 or 3000 you can slide in silicon transistors in with little bad effect.
You do, of course, know that Corvairs came with a Delco radio like any other GM car of the era. That POS Motorola is a cheap aftermarket unit. Those transistor leads are probably work hardened from vibration the way they are just hanging there.You would think the owner would acquire a Delco for the originality and quality, unless this is just a project to see what you can do with that thing.
Yea, I'd want to listen to the radio while dying in one of the most dangerous cars ever make. Really hate working on something that someone else has been messing with.
As bad as I hate to admit it, I think those mid '90's $29 AM/FM/cassette tape car stereos were built better than this one. I generally like Motorola stuff; but, they dropped the ball on the build quality of this unit.
As i said before The 2SA72 transistor has always been a problem component. Save a lot of time when service these early car radios and suspect these transistors.
I could not find much information online about the radios used in Corvairs, most of what I found was about the ones used in the first generation Corvairs which was a four tube hybrid model that used a PC board. It's odd that they would have a solid state radio with hard wiring but a tube radio with printed circuits? This could be an aftermarket unit, but then again it could have been OEM, Motorolla built a lot of radios for Chrysler and Ford in the 1940s, 50s, and 60s up until the Ford buyout of 1961, often with the MoPar or Ford names stamped on them. Everyone assumes that G.M used nothing but Delco but who knows whether Delco actually made everything that they had their name on? One thing for sure is that the use of Bad All caps does not inspire much confidence in this thing.
The coil in the output stage seems to be a constant current source for the output transistors. It allows the AC signal to go to the speaker while permitting adequate DC bias for the OP stage. It is an odd way of doing it. Not sure why they didn't use a cap coupled OPS.
Enjoyed going along on your troubleshooting adventure. Yea corrosion gets in those old things can really throw you off track on some odd stuff. I agree on the poor build quality. Guess all generations had them. Nowaadays we just have nearly all cheap junk resulting in poor quality.
3:10 I like that germanium push-pull going into a center-tapped speaker. I've only seen that in certain RCA and maybe Bush or Pye portables; it seem like an ingenious way to get around using those hideous micro-miniature Japanese output transformers that made everything sound like crap during those years. Might be a problem if the speaker fails, though.
+No Name On second look, it almost seems to be an inductor serving as an autotransformer, never seen anything like that before. As I'm watching through the end of the video it's more obvious. I would think the same transformers they normally used in push-pull circuits would work. I wonder if they were just trying to save copper or had other reasons for this design.
I am a little surprised to see a Motorola radio instead of a Delco radio here. I did not realize Motorola car radios where such total trash - that thing is an insult to "Made in America". (I mean the radio - leaving the topic open on the car)
+Alan Maier Maybe the Corvair was so short on space or ventilation that the usual Delco with a giant heat sink in the back was less practical than a push-pull design. I'm surprised a Motorola wasn't better made, though, they have generally had a good reputation for quality.
I have a Blaupunkt Frankfurt radio that came with my 1968 vw beetle when i got it its an am and fm radio with single speaker as now it has a blown capacitor and i can't seem to get the MFD or voltage value on it they look they are plastic as i want to use this radio again as i can't figure out what the capacitor values are everything inside the unit is in tact. as im not sure if the single speaker output can handle four speakers. as i want to use those instead of putting a speaker to the left of the speedometer in which all 1958 -1977 standard vw beetles had as the radio was optional equipment for them then. as i know the oval window beetles they had a Motorola tube radio on the bottom of the center of the dash and above it is the speaker grille is where the speaker is on these oval window vw bugs from late 1952- 1957. as im using radio surpressed spark plug cables on mine and electronic ignition so i don't hear any noise on the AM side when the previous radio did work as not sure on the modern retrosound radios avilable for it now if they are good or not.
I just bought an old Motorola AM car radio hoping to teach myself, or hoping others might be willing to teach me, how to clean and fix it. I imagine my first task is to find the right schematic but I'm already stuck at this first step. Looking at the numbers stamped into the side - 524 6295, I thought I'd find a copy of the Photofact. But I don't find any reference to that radio at all. Can you or someone help? Thanks!
My only two cars are Corvairs and they work just fine. You must have been listening to Ralph Nader. Those radios were in most American cars of the era so don't denigrate the car because of the radio..
Wow an american made radio using japanese transistors? Those 2SAs? OK I take that back - saw the motorola symbol on one of them when you zoomed in. That audio output stage is choke coupled push-pull as opposed to choke coupled single-ended like Delco radios. Try something like a 12 volt center tapped power transformer on the 12 volt side - leave the 120 volt side open. Oh well so you did - I'm commenting as I watch the video - nevermind.
![Lp. Последняя Реальность #107 РОДНОЙ ДОМ [Финал] • Майнкрафт](http://i.ytimg.com/vi/IK3QKzKUlHM/mqdefault.jpg)
Corvairs used Delco and RCA radios. I know because I have 25 Vairs..
You and radiotvphononut have the best 2 channels on youtube.
Hey Shango. I think the fact they use 262.5KHz IF frequency might have to do with the harmonics generated by a mechanical ignition in old-style cars. Opening and closing contacts in the HV distributor generate very dirty square wave signals which are rich in harmonics, or so I've learned. Using the 262.5KHz might be an attempt to avoid those harmonics creating that annoying buzzing noise one heard in old CRT tv's and tube radios when a car drove by.
Like your videos as always :) they're real treasures of fun and info mixed in the right proportions
I did not know that all the slugs moved like that when tuning.
Great info. Look forward to the Russian germanium transistor vid.
Thanks
Carl
Motorola was the first to build a good car radio, thus their name MOTOR Ola built for cars.
Nice video, what a rat's nest of wires. Looks like a good fix. You're obviously in LA mentioning KNX, KFI, etc. Torrance here.
Grueling troubleshooting session(s), but one damn nice catch and save. Ralph Nader thanks you!!
Weren't all General Motors radios made by Delco? This one appears to have been an aftermarket radio probably installed by the dealer as radios were not standard?
I get the heebie-jeebies every time you poke your index finger into a radio or TV. Amazing that you're still able to do so. At least with a transistor car radio you're not going to get zapped. Take care!
Also when I was servicing RCA 16mm projectors, they used those bakelite body and red end goop capacitors, they typically lost 90% of their capacitance in the first year.
Another tip: car radios typically had "belt and suspenders" biasing, robust enough so you could swap in silicon transistors into the low power stages with no problem. For instance on a typical TransOceanic 1000 or 3000 you can slide in silicon transistors in with little bad effect.
Thank you for the upload.
Very nice project.
Great troubleshooting video - gives me hope I can sort out my scope repair!
Cheers, John
Excellent! I would have never guessed what the problem was.
I'm surprised the transistors didn't burn up.
You do, of course, know that Corvairs came with a Delco radio like any other GM car of the era. That POS Motorola is a cheap aftermarket unit. Those transistor leads are probably work hardened from vibration the way they are just hanging there.You would think the owner would acquire a Delco for the originality and quality, unless this is just a project to see what you can do with that thing.
Motorola was always known for durability. This poor thing would rattle apart. Good idea, never thought a power transformer would work as an output.
Great trouble shooting has always. I am looking forward to more videos
Yea, I'd want to listen to the radio while dying in one of the most dangerous cars ever make. Really hate working on something that someone else has been messing with.
As bad as I hate to admit it, I think those mid '90's $29 AM/FM/cassette tape car stereos were built better than this one. I generally like Motorola stuff; but, they dropped the ball on the build quality of this unit.
As i said before The 2SA72 transistor has always been a problem component. Save a lot of time when service these early car radios and suspect these transistors.
That radio looks like it was built in a shack on someone's kitchen table, using an icepick heated on a kerosene stove as a soldering iron!
I could not find much information online about the radios used in Corvairs, most of what I found was about the ones used in the first generation Corvairs which was a four tube hybrid model that used a PC board. It's odd that they would have a solid state radio with hard wiring but a tube radio with printed circuits? This could be an aftermarket unit, but then again it could have been OEM, Motorolla built a lot of radios for Chrysler and Ford in the 1940s, 50s, and 60s up until the Ford buyout of 1961, often with the MoPar or Ford names stamped on them. Everyone assumes that G.M used nothing but Delco but who knows whether Delco actually made everything that they had their name on?
One thing for sure is that the use of Bad All caps does not inspire much confidence in this thing.
The coil in the output stage seems to be a constant current source for the output transistors. It allows the AC signal to go to the speaker while permitting adequate DC bias for the OP stage. It is an odd way of doing it. Not sure why they didn't use a cap coupled OPS.
That transformer can't be that hard to find. Start searching the Stancor/Merit etc. numbers in the Sams.
It's hard to believe that thing came from a factory built like that.
I have a CRC marine corrosion spray that would stop the corrosion on that radio right in it's tracks.
Enjoyed going along on your troubleshooting adventure. Yea corrosion gets in those old things can really throw you off track on some odd stuff. I agree on the poor build quality. Guess all generations had them. Nowaadays we just have nearly all cheap junk resulting in poor quality.
Spot on Retrochad... 😆
3:10 I like that germanium push-pull going into a center-tapped speaker. I've only seen that in certain RCA and maybe Bush or Pye portables; it seem like an ingenious way to get around using those hideous micro-miniature Japanese output transformers that made everything sound like crap during those years. Might be a problem if the speaker fails, though.
+No Name On second look, it almost seems to be an inductor serving as an autotransformer, never seen anything like that before. As I'm watching through the end of the video it's more obvious. I would think the same transformers they normally used in push-pull circuits would work. I wonder if they were just trying to save copper or had other reasons for this design.
I am a little surprised to see a Motorola radio instead of a Delco radio here. I did not realize Motorola car radios where such total trash - that thing is an insult to "Made in America". (I mean the radio - leaving the topic open on the car)
+Alan Maier Maybe the Corvair was so short on space or ventilation that the usual Delco with a giant heat sink in the back was less practical than a push-pull design. I'm surprised a Motorola wasn't better made, though, they have generally had a good reputation for quality.
Some dealers ordered their cars with no radio and sold the cheaper Motorola radios themselves. GM did NOT like that at all.
all my vairs have delcos
33Hz.. Heh.. Awesome. Also, i want the transformers!
2N2955 power transistors might be worth a try for the output stage.
good build quality though, Here we have xD
I have a Blaupunkt Frankfurt radio that came with my 1968 vw beetle when i got it its an am and fm radio with single speaker as now it has a blown capacitor and i can't seem to get the MFD or voltage value on it they look they are plastic as i want to use this radio again as i can't figure out what the capacitor values are everything inside the unit is in tact. as im not sure if the single speaker output can handle four speakers. as i want to use those instead of putting a speaker to the left of the speedometer in which all 1958 -1977 standard vw beetles had as the radio was optional equipment for them then. as i know the oval window beetles they had a Motorola tube radio on the bottom of the center of the dash and above it is the speaker grille is where the speaker is on these oval window vw bugs from late 1952- 1957. as im using radio surpressed spark plug cables on mine and electronic ignition so i don't hear any noise on the AM side when the previous radio did work as not sure on the modern retrosound radios avilable for it now if they are good or not.
I just bought an old Motorola AM car radio hoping to teach myself, or hoping others might be willing to teach me, how to clean and fix it. I imagine my first task is to find the right schematic but I'm already stuck at this first step. Looking at the numbers stamped into the side - 524 6295, I thought I'd find a copy of the Photofact. But I don't find any reference to that radio at all. Can you or someone help?
Thanks!
Sad to see a Motorola product bodged together like that. I had always thought much better of them.
Corvair, unsafe at any speed. Corvair Radio, unusable at any frequency.
Hey, Ralphie boy...
You have built the Carlson Superprobe XVI ?
Where is the online link to get russian germanium transistors??
retrochad? lol
0:01 what about that voice? LOL
One of those chassis grounds?
Is 20mV AC at an AM detector diode normal?
gawd scrap it, part it out, whatever.. just stick a Pioneer in the thing and be done w/ it! lol, kidding, I love the longshot ones the most.
This dose not look like a Motorola design to me. The output transistors are Motorola but not the radio.
My only two cars are Corvairs and they work just fine. You must have been listening to Ralph Nader. Those radios were in most American cars of the era so don't denigrate the car because of the radio..
they used the cheapest crap that they could make and charged $69.00 for them
spray cleaner on the hole inside radio as its lost
Messy assembly provided by Motorola , I think a pcb assembly would not have killed this company´s profit with this product.
Retrochad is burnt
Who not go for broke and stick another Russian Transistor in place of the converter transistor and see if that does the trick.
35:20 Is that Ringo's mom? That's what I'd call "copywrong".
Was this radio engineered by a democrat?
I enjoyed the trouble shoot.
Don
This radio is proudly manufactured by the department of hope and change.
DELCO - Motorolee?
Sloppy, rusty construction. Sounds like a Vega.
Wow an american made radio using japanese transistors? Those 2SAs?
OK I take that back - saw the motorola symbol on one of them when you zoomed in.
That audio output stage is choke coupled push-pull as opposed to choke coupled single-ended like Delco radios. Try something like a 12 volt center tapped power transformer on the 12 volt side - leave the 120 volt side open.
Oh well so you did - I'm commenting as I watch the video - nevermind.
my corvairs all have delco radios,,, lot better made
" I usually don't complain about the way things are built but". OK. Then I'll help you complain. That thing looks like crap. LOL.
Frustrating to watch. Traditional fault tracing in radios _starts_ at the output and works backwards toward the input.
Then why watch ?
I am tearing up the road going 5 miles an hour.